1. Field of the Invention
The invention is related to the structure of a two-stroke internal combustion engine. Especially, it involves a type of engine that converts the instant power of fuel into cyclic linear movement of an external piston.
2. Description of the Prior Art
Current internal combustion engines (engine) are mainly two-stroke or four-stroke. Please refer to FIG. 1 for the structure for a common two-stroke engine. Its cylinder block 10 has an air intake 11 and an air exhaust 12 on two opposite sides. A piston 13 has a sealing piston ring 14 inside the cylinder block 10. One end of a connecting rod 15 connects to a piston pin 16 inside the piston 13. The other end of the connecting rod 15 connects to a crankshaft 18 inside a crankcase 17 at the bottom of a cylinder block 10. When the piston 13 is in an upward stroke at the top of cylinder block 10 to compress the mixed fuels, a spark plug 19 ignites the fuels to explode and force the piston 13 in a downward stroke. Then through the crankshaft 18, the power is output. When the piston 13 is below the air exhaust 12 in a downward stroke, the combustion waste gases are exhausted. Upon exhausting the waste gases, the air exhaust 12 experiences a Venturi effect that builds up pressure in the crankcase, so the pressure in the top of the cylinder block 10 becomes negative. The air intake 11 (with check valve) sucks in mixed fuel gases. At this moment, the piston 13 uses the rotational power from the connecting rod 15 and the crankshaft 18 to generate an upward stroke and compress the mixed fuel gases again and ignite to explode. From the description above, it is known that the two-stroke engine has advantages in simple structure, low power loss and high power output. Since the piston 13 passes by the air intake 11 and the air exhaust 12 on two opposite sides of the cylinder block 10 in an upward stroke and a downward stroke, the crankcase 17 cannot store engine oils inside. But because mechanical movement needs lubrication, the two-stroke engine needs lubricants in its fuels. Thus, combustion causes lubricant film formations and the combustion is apparently incomplete. This leads to emission of polluting waste gases that cause environmental issues. The objective of the invention is to provide for a two-stroke engine to minimize pollution from emission of waste gases and increase its power output.